Change-speed transmission for aircraft



2 Sheets-Sheet 1 O. H. BANKER KM K Rb Filed July 4, 1942 CHANGE-SPEED TRANSMISSION FOR AIRCRAFT Feb; 27, 1945.

Feb. 2?, 1945. o BANKER I 2,370,131

CHANGE-SPEED TRANSMISSiONFOR AIRCRAFT Filed July 4, 1942 zspeets-sheez 2 new Feb. 27,1945

CHANGE-SPEED TRANSIVHSSION FOR AIRCRAFT Oscar H. Banker, Evanston, Ill., assignor to New Products Corporation, Chicago, 111.", a corporation of Delaware Application July 4, 1942, Serial No. 449,717

. I g V 1 0 Claims. This invention has. to do with a change-speed transmission particularly suitable for use between the engine and'the propeller of aircraft and relates more particularly to and has as a general object, the provision of an improved combination and character of power trains in such transmission, expediting shifting of the power trains and enabling a higher speed transof a. 'jaw clutch in a partially meshed condition, wherein the teeth are adapted to ratchetin one" direction to permit relative rotation of, the counterparts but to catch upon one another for preventing relative rotation in the: opposite direction;

Fig. '3 is a view taken similarly to Fig.

1 through a modified form of the invention emmission of said trains to serve as a transmitter of cranking force from the propeller to the engine while conditioned to permit driving of the propeller from the engine through 'a power train of lower speed transmission.

plate employed in'the speed responsive clutch A more specific object of the invention is the provision, in an aircraft change-speed transmission, of a lower sp'eed'power train operable to allow the propeller to overrun the engine so said train can remain mobilized during drive of the propeller through a higher speed train which contains a jaw clutch of which, toothed counterparts are meshable, when synchronized, to establish such higher speed train in driving relation between the engine andpropeller, and of which counterparts the teeth are bevelled to'facilitate a condition of partial meshing and consequent ratcheting of one counterpart over the other in one direction to renderthe higher speed train incapable of transmitting driving force from the engine to the propeller so the engine is operable to drive the propeller through the lower speed train, and such bevelling further causing the shaft for the propeller teeth in said partial meshed relation catch to prevent ratcheting when the propeller tends to overrun the engine whereby said higher speed train is effective as a transmitter of cranking force from the propeller to the engine.

The invention further contemplates speed responsive means in control of said clutch and becoming enabled, when subjected to speeds:

' above a predetermined minimum, to'cause adjustment oi the clutch from the partial meshed relation to a substantial meshedrelation wherein the counterparts are rotatable in unison in both directions, upon synchronization of the counter parts. I

These and other desirable objects inherent in and encompassed by the invention will be better understood from the ensuing description together with the annexed drawings, wherein: v

Fig.1 is a sectional view taken longitudinally through a planetary gear type of change-speed integrally with an actuator,

ploying parallel shafts; v I Fig. 4 is a plan view of a spring abutment actuating means shown'in Fig.- 3; and

FigJ'S is'a view taken like Figs. 1 and 3 through a. .third form of transmission embodying the principles of this invention.-

Referring now to Fig. -l, the transmission apparatus there shown is enclosed within a gear box 10 open at its back end, which is disposed at the right'as viewed in Fig. 1, and which is secured .to the'front end of an aircraft engine ll by machine bolts '92. The drive shaft ll-of the transmission may constitute a portion of the engine crank shaft, and is arranged coaxlaily with a driven shaft. 14 which serves as a. propeller l5 of an aircraft-(not shown) upon which the apparatus is installed.- A back end portion 16 of reduced diameter of the-driven shaft is piloteddpon a bushing unit I1 a recessed portion l8 of the drive shaft l3. An intermediate portion of .the driven shaft is journaled within a ball bearing unit I! which is carried'in the front wall of the gear box l0.

A planetary gear unit 20 includes a. sun gear 2|, a plurality of ,planet' gears 22 of which one planetary gear unit 20 has secured therein a, pluralityof axially directed and clrcumferentlally spaced shafts, 25'upon which the planet gears 22 are respectively joumaled.

The'sun gear 2| is rotatively mounted upon. a bearing sleeve 26 which in turn is supported upon the driven shaft l4. Said sim gear is formed 21 of a conventional structure forming an element of an ovemmning holding device or brake of the overrunning brake 28 include a ring 29 secured non-rotatively to the gear box by a. plurality of circumferentially spaced bolts ill in coaxial relation with the actuator member 21, and

'circuml'erentlally spaced rollers 3| disposed betransmission construction according to the principles of the present invention;

Fig. 2 is an enlarged fragmentary view taken on a line 2-2 of Fig. 1 and illustrates the teeth tween the actuator member 21 and ring 28. The actuator member 21 is so constructed in a manner well understood in the art, that it is operable to cause the rollers 3l to react upon periphery of the ring 29 for preventing ,clockwise 28. The other elements the inner rotation of said actuator member 21 and hence -of the sun gear 2| relatively to the ring 29, with is upon the front end of a drum 32 of which the back end is secured by bolts 33 to a flange 34 upon the drive shaft l3.

A back plate 35 constituting a part of the carrier 24 has a hub-like sleeve portion 39 projecting rearwardly in splined relation with the driven shaft l4 as indicated at 31. One counterpart 39 of a jaw clutch39 is splined at 49a to the outer periphery of the member 39. This counterpart 38 has a group of circumferentially spaced axially directed teeth 49 which are meshable with a likewise arranged group of teeth 4| upon a counterpart 42 of said clutch 39 that is secured to the driving shaft flange 34 and to the ring gear 23 by the bolts 33. In Fig. 2 the end faces 43 of the teeth 49 are seen to be beveled spirally of the clutch in such a direction that the leading edges 44 of said faces extend a greater distance rearwardly than the trailing edges 45. A corresponding bevel is placed upon the end faces 49 of the teeth 4| whereby the trailing edges 41 of these faces extend forwardly a greater distance than the leading edges 49 thereof. Manipulation of .the clutch 39 for adjusting it from a partially I meshed condition illustrated in Fig. 2 to a substantially meshed position is accomplished by sliding the counterpart 98 axially rearwardly upon the splined connection 49.

Speed responsive means for controlling the axial positioning of the clutch counterpart 38 includes centrifugal weight members 49 and helical springs 59 of which one of each is shown in Fig. 1. These weights 49 and the springs 59 are distributed alternately circumferentia'lly about the carrier axis. Each weight 49 has apertured bifurcations 5| that straddle an apertured head 52 therebetween that are integral with certain of the planet gear shafts 25. Pivot pins 53 for the weights 49 are disposed within the apertures of said heads and in the bifurcations of the respectively associated'weights. Each weight 49 has a boss 54 that extends radially inwardly of the transmission into abutting relation with the front end of a ring 55 slidable axially upon the,

clutch counterpart 38. A light helical spring 55 is disposed about said clutch counterpart between said ring 55 and a shoulder portion 51 of said counterpart. counterclockwise rotation of the weights 49, as the weight shown in Fig. 1 is viewed in that figure, will cause rearward displacement of the bosses 54 and compression of the spring 56 whereby the latter will time the counterpart 39 into mesh with the counterpart 42 with a relatively small yieldable force.

The aforesaid springs 59 are for opposing the centrifugally developed force of the weights 49 in urging the'ring 55 rearwardly. The springs 59 are contained in cylindrical spring chambers 59 which are disposed within holes 59 of the planet carrier, and the front open ends of the pring chambers are flanged outwardly at 99 for preventing rearward displacement thereof. A bolt 9| is disposed coaxially Wi hin 6 f h spring chambers 59 and coaxially within the respectively associated spring 59 andhas upon its forward end a head 92 for reacting against the forward end of said associated spring. The back end of each bolt 9| projects rearwardly. through a hole 93 in its associated spring chamber whereby the bolts r'nay be projected rearwardly through said hole 93 incident to compressing their associated springs 59 while the back ends of those springs react against the back closed ends of their respective spring casings 58. Apertured ears 54 upon the ring 55 are connected with threaded sections of reduced diameter upon the back ends of the bolts 9| by nuts 95 which press said ears firmly against shoulders 99 of the bolts. Thus the ring 55 is connected rigidly to the reciprocal bolts 9| and is normally held at the forward limit, determined by abutment of the ears 54 with the .back end of the spring chambers 59. A snap ring 91 near the forward end of the jaw clutch counterpart 38 abuts against the ring 55 to limit the axial rearward displacement of the counterpart 39 with respect to the ring 55 under the force exerted by the light clutch-engaging spring 59.

Operation of the first embodiment Normally the springs 59, in reacting against the back ends of the spring chambers 59 apply a forward force against the heads 62 of the bolts 9| and thereby retain the ring 55 at its forward reciprocal limit against the' back ends of the spring chambers. When the ring 55 is in this forward most position it acts against the snap ring 91, in opposition to the yieldabl force of the clutch-engaging spring 55 for limiting backward displacement of the clutch counterpart 39 to a partially meshed relation with the counterpart 42 as that illustrated in Fig. 2. In this latter mentioned figure it will be seen that the clutch counterpart 42 may rotate counter-clockwise, the direction indicated by the arrow thereon in Fig. 2, relative to the counterpart 39 incident to causing the teeth 4| to ratchet over the teeth 49 while sliding the end faces 49 of the teeth 4| along the end faces 43 of the teeth 49. There is 'suillcient clearance between the forward end of the clutch counterpart 38 and the planet carrier plate 35 to permit forward displacement of said counterpart against the yieldingurge of the spring 55 and as caused by the camming action between the tooth end faces 43 and 45 during the aforesaid ratcheting of the counterpart teeth. A

the transmission will first transmit power to the propeller l5 through a speed reduction power train, whereby suiilcient engine speed is attainable for the development of high power by the engine and torque multiplication is obtained through the transmission to the propeller. This speed reduction power train includes the drum 32 which is driven from the drive shaft l3, the ring gear 23, planet gears 22 which are caused to rotate counter-clockwise about their individual axes while reacting against the sun gear 2| and moving orbitally thereabout incident to rotating the planet carrier- 24 counter-clockwise at reduced speed, saidplanet carrier, the sleeve hub 39 of said carrier, the splined connection 31 bee 7 2,870,181 tween the sleeve hub 36 and the'drivenshaft ll,

said driven shaft and the propeller l5. Because of the resistance to rotation of the propeller and hence of the planet carrier 24 connected therewith the axle shafts 25 of the planet gears 22 resist orbital movement and thus cause the planet gears 22, when rotated counter-clockwise about their individual axes bythe force imparted thereto by the counter-clockwise rotating ring gear 23, to tend to drive the sun gear 2i clockwise. But as eirplained. hereinabove clockwise rotation of the sun gear2i is prevented by the one-wa brake device 28.

During operation of the just traced, the clutch counterpart .38, which is connected for rotation with the planet carrier 26 will be rotating counter-clockwise as indicated by the arrows in Fig. 2, more. slowly than the clutch counterpart 32 which is connected for rotation in unison with the drive shaft 53. Consequently during operation of the-first speed first speed power train chronization period of the clutch counterparts l2 and-38' the planet carrier 2i and the ring sear 23 which are rigidly connected respectively with the counterparts 38 and 42 will approach the power train the clutch counterpart d2 ratchets A over the clutch counterpart 38.

Upon the attainment of a predetermined mini mum speed the planet carrier M will rotate sun ciently'iast for causing the weights 39 to throw radially outwardly from the full line position shown in Fig. 1 to positions corresponding to the dotted line position shown for the weight 39 in Fig. 1:. This pivotal movement'of the centrifugal weights occurs about the axis in their respective pivot pins as and causes forward displacement of the bosses b t and hence of the ring against the urge of the springs 58, the augmentation in the force of the spring 56 as it.is compressed by such iorward movement of the ring as being substantially negligible in opposing radial out ward displacement of said centrifugal weights. The spring 58 is made very light so that the force created therein for pressing the counterparts into ratcheting relation will notbe so great as to impair the-clutch teeth or cause undue same speed and will eventually attain the same speed concurrently with synchronization of. the

counterparts 38 and 42, and when this occurs the a clutch counterparts mesh to transmit driving force directly between the drive and driven shafts independently of and without applying force upon the teeth of the gears in the planetary gear unit. At the beginning or the synchronization period the sun gear 2| was reacted upon by theplanet gears 22, then rotating about their individual axes,

in such a manner thatit had a tendency to rotate clockwise, which tendency was overcome by the one-way holding device 28; and since at the end oi the synchronization period the sun gear attains the clockwise rotational speed of the ring gear 23, said sun gear, during the synchronization period,

' is accelerated counter-clockwise from zero speed to the speed of the ring gear.

The one-way holding device Npermits this counter-clockwise rotation of the sun gear 2| and in doing so lends to the lower speed power train the character of an overrunningpower train whereby. the drive shaft 93 may decelerate with respect to the driven shaft i4. When the drive shaft deceleratesto the same speed as the driven shaft, the spring 56 ratcheting noise even after the increase in the pressure exerted by said spring by the backward displacement of thering 55 incident to radial outward displacement of the centrifugal weights.

So long as power is transmitted through the lower speed power train in the manner described the ratcheting of the jaw clutch counterparts will continue and said power train will remain established. in driving relation between the engine and the propeller. However, after the centrifugal weights lt have been thrown outwardly for advancing the ring 55 the speed responsive control is so conditionedthat a change-overcan be made into ar -higher speed power train, which in this instance is a power train of one to one driving ratio. This higher speed power train is a reasonably low speed, to drive the propeller at the desiredspeed.

will slide the counterpart 38 rearwardly into meshed relation with the counterpart l2, establishing thehigher speed train. Power is then transmitted from the drive shaft-l3 to the drive counterpart 62, thenceto the driven counterpart 3B, the sleeve-dike hub 36 of theplanet gear carrier, and the splined connection 31 to the.

driven shaft it. Meanwhile, and during operation of the higher speed power train, the .sun gear 21 and the one-way holding. device actuator member 2? overrun'the ring is of said holding de-.&

vice as permitted by the rollers 31.

The shift into the higher speed. power train from the lowerspeed train'will be executed after the aircraft has finished take-oi? and climbed to the desired altitude where the aircraft is drivable at ordinary cruising speeds with the application of lesstorque to the propeller. Establishment of the 'higher speed'powei train between the engine'and the propeller under ordinary cruising conditions enables the motor, while rotating at A shift down into the lower speed power train for main driving the propeller at higher speed may be necessary in maneuvering the craft or in obtaining rapid climb. It is incurredby throtestablished bveausing .the jaw clutch counterparts to mesh and is brought about by closing or partially closing the engine throttle so the drive shaft wand the clutch-counterpart 42 connected therewith will slow down to synchronism with the counterpart 38. Thus the shift from the lower speed train to the higher speed train is effected at the will of the operator.

tling down the engine and hence the propeller and planetary carrier directly connected therewith, toa speed at which the springs in are effective for drawing. the centrifugal weights 49 in-- wardly whereby said springs, upon expanding, will draw the ring 55 forwardly together with the snap ring t1 and theforwlard clutch counterpart 88 for demeshing the clutch 8% and thus demobilizing the higher speed train; Drive is then 7 available through-the lower speed train simply m the execution of a shift from thelower speed power train to the power train of higher speed and upon the slowing down'of the drive shaft 63 comparatively rapidly because of the braking action of engine compression, the propeller 95,

because of its inertia and also because of the air stream acting thereon as a result of the forward movement ofthe craft, will decelerate relatively slowly. It follows that during this syn-.

by speeding up .the engine and the drive shaft is whereupon the one-way holding device 28 again becomes effective for preventing clockwiserotational tendencies of the sun gear 2 i. It should-be noted that the two speed changespeed transmission just described is always conditioned so that one or the other of the power trains is mobilized for the transmission of power irom the engine to the propeller. There is no neutral. It follows that the craft will never be stranded in flight with the engine disconnected from the propeller.

Another important operating feature of the transmission is its ever present potential employment as a cranking force transmitter between the propeller and the engine.

It was explained hereinabove that the ring 55 is limited in its forward displacement by the ears 64 abutting against the back ends of the spring chambers 58 so that when the apparatus is at rest the spring 56 can be effective for urging the counterpart 38 rearwardly into the partial meshing relation with the driven counterpart 42 illustrated in Fig. 2, but is unable to force the counterpart 38 any farther rearwardly or into mesh with said counterpart 42. During this partial meshed relation of the clutch counterparts 38 and 42 the drive counterpart 42 is free to overrun the counterpart 38 as it does during operation of the lower speed train. Such overrun of faces 43 on the teeth so that when the counterpart 42 is rotated counter-clockwise with respect to the counterpart 38 a leading portion of the faces 46 will first abut against trailing portions of the faces 43 so that a sliding camming or ratcheting relation is established between the clutch counterparts. However should the propeller I5 and the driven shaft I4 tend to overrun the drive shaft I3 and the counterpart 42 con: nected therewith, the leadingfaces 44a of the clutch teeth 40 will abut flatly againstthe trailing face portions 48a of the teeth 4|, and this catching of the teeth 40 upon the teeth 4| will cause the drive shaft I3 and the engine connected therewith to be rotated with the propeller. Hence a forward rotational cranking force is impartable from the propeller to the engine through the higher speed power train even though that power train is disestablished for the transmission of driving force from the engine to the propeller. Less torque may be applied to the propeller for cranking the engine through the higher speed train than through the lower speed train inasmuch as the lower speed train, if power were transmitted through it from the propeller to the engine would tend to cause the engine to rotate at an overspeed with respect to the propeller.

It will be further noted that the partially meshed clutch 39 mobilizes the high speed power train when the centrifugal weights 49 are in their radial inward position as when the craft is at rest upon the landing field. Therefore, the propeller may be employed for manually cranking the engine for initially starting it although the lower speed power train that is overrumiing in character is initially available for driving the propeller from the engine under take-off conditions.

Since the transmission is operable for transmitting cranking force from the propeller to the engine through the higher speed power train,

peller and the planet gear carrier whereupon the inertia weights will be forced inwardly by the springs 50'and the ring 55 pulled forwardly for adjusting the clutch 39 from the substantial meshed condition to the partiallymeshed condition shown in Fig. 2. This adjustment of the clutch 39 will not impair the mobilization of the higher speed power train for serving as a cranking force transmitter between the propeller and engine so that by diving with the craft for causing the air to react with sufllcient force against the propeller blades for causing it to rotate forwardly, that is counter-clockwise, the clutch '29 will impart said clockwise rotation to the engine for cranking the same'.

In view of the importance of the partial engagement of the clutch counterparts 38 and 42,

provision is made for their periodic inspection.

through holes H and H0 respectively in the bell 32 and the gear box. A threaded plug P normally closes the hole H0.

The modificationshown in Fig. 3 has operating characteristics similar to that shown in Figs. 1 and 2 but employs parallel shafting instead of planetary'gearing. Another difference between the modification of Fig. 3 and that of Figs. 1 and 2 isthat all power trains are speed reduction trainathere being two power trains one constit'uting a starting speed power train and the other a cruising speed power train.

The transmissionhhoused in a gear box I09, transmits power from a drive shaft IOI which may be the end of an engine crank shaft, to a drivenshaft I02 which is ',drivin gly connected with a propeller I03. 'Ihe'lower speed power train or starting speed power train includes a relatively small diameter hollow shaft I 04 splined at I05 to the drive shaft IOI and to a hollow gear cluster shaft I06 at I01, a gear I00 of relatively small diameter on said cluster, a gear I00 journal'led at IIO on a hub III of an overrunning clutch actuator member II2, an overrunning clutch device 3 (including a cylindrical portion I I 4 of the gear I09, said actuator member II2 and'overrunning clutch rollers I I5 disposed between said actuator member and the cylindrical portion II4), the hub III of the actuator member I I2 that is splined at II9 to the driven shaft I02, and said driven sh aft to the propeller I03. The overrunning clutch I I 9 is designed to prevent-the gear I09 overrunning the actuating member H2 in the clockwise direction as viewed from the front orleft of the transmission as shown in Fig. 3, but permits the actuator member II2 to overrun the gear I09 in said clockwise direction. The construction of such an overrunning clutch device is well understood in the art.

The higher speed power train includes the aforesaid hollow gear cluster I06, 9. gear I'II integral with said gear cluster, a gear II8 meshed with the gear II! and journalled upon bearings I I9 for rotation coaxially of and about the driven shaft I02; a jaw clutch counterpart I20 of a jaw clutch I2I, a counterpart I22 of said Jaw clutch. (when the teeth 12: and m respectively upon said counterparts I20 and I'22 are meshedin a manner presently to be described), a splined connection I25 of the counterpart I22 with the driven shaft I02, and through said driven shaft to the propeller I03. ;During operation of the higher speed train the actuating member III of the overrunning clutch device III will be rotated clockwise at an overspeed with respect to the gear 589 as permitted by the clutch rollers Hi.

The gear cluster M6 is a full floating-unit, it being journalled at its two. ends by means of ball bearirig units M6 and III which are supported respectively in the front and back end walls of the gear box. The ballbearing units 128 and M9 also respectively 'inithe front and back walls of the gear box rotatlvely carry the hollow driven shaft nor. :1

The driving counterpart iii) oithe overrunning jaw clutch Ml is splined to the hub of the gear M8 at m and is axially slidable upon said gear hub between reciprocal limits in which the clutch teeth lit and lit are respectively ina' partially meshed condition and a substantially meshed condition as explained hereinabove with respect to the clutch teeth in the first embodimeat. in Fig. 3 the clutch teeth i253 and i2 3 are illustrated in the partially meshed condition.

Speed responsive means for controlling the axial position of the drive counterpart. Hill) is carried by the gear lid. Said speed responsive means or mechanism includes centrifugal weights tilt spaced apart diametrically with respect to said year, although draitsmans license has n in 8 to show but one of the weights 1385 a helical spring i212 or which there are two diametrically across the gear Md from other and spaced at circumferehtially of r wi h respect to the weights till. Said are pivotfl 3 carried icy pins 333 am it in h the gear MG. 3, eerishe-rm in iniiig. l. portions 936 of the weights oia loo has central opening receives'a :l'or'ward portion of the drive s t he .iate to he slid H86 hear op which in of the respecate holes This eirpah the springs tends to hold rward most position illuswhich position is determined G3: the out side see against 1e gear MS. The plate ring; i iii upon r "placement of c'iut l1 cow: aptly necessary to establish -="l'id re W 523 reacts against the id a 'ainst a shoulder i l! said counterpart only into the partialiy meshed relation t ri ed coimterpart. However, is lent clearance between the front end of said cart i223 the trout iace oi the gear permit forward dispiacemeutoi' said courioursuaht to ratcheting oi the clutch teeth on ofthe plate 13% iil'illle -is oi the weights When active tosses i 36 which may LED above described the springs I32 will be eflective for holding the plate I35 and the tails I36 of the centrifugal weights iii forwardly and the weights themselves in their radially inwardly disposed position. The parts will occupy their respective positions illustrated in Fig. 3. It will be noted that the gear 8 is driven at a speed constituting a function of the drive shaft speed during operation or the lower speed train, so

that when the drive and driven shafts reach respective predetermined speeds the gear 8 will reach a corresponding predetermined minimum speed at which the weights l3! will fly radially outwardly in opposition to the force of the springs H2 and thereby displace the elliptical plate E35 rearwardly, enabling the spring I46 to press the clutch counterpart I20 a greater distance axially rearwardly'before abutment is had by the snap ring ldii at said plate lSfi. When the weights iiil are in their radially outward position the spring Mt can advance the counterpart HG rearwardlysuficiently far for efiecting said substantial meshing oi the clutch teeth i253 and 826, although so long as the lower speed train is established and in operation ratcheting of the teeth i523 arid ii l will continue.

ilt'hile driving the propeller from through the lower speed power train at a speed sumcientiy high for the weights it'd to be in their:

outer radial position, the operator can initiate a for establishing second or higher speed power train between the engine and propeller simply icy closing the engine throttle for causing the engine, the shaft tilt, shaft M35, gear c1115- itfi and M8 and the clutch ooun- V ter gears tor-part to slow down whereas the inertia and air stream action upon the her Silt result in it decelerating more slowly and in a correspeeding slower deceleration he driven shaft i652; the cverrimnihg' clutch actuator H2 splihed to said driven shait the clutch counterpart i spline-d to said driven she m, This relatively slower deceleration of the propeller and said parts connected for rotation rewith with respect to the engine and the aim parts driv ingly connected therewith ismade possible by the overrurmizig clutch Eventually the clutch counterpart tilt wili decelerate to syhchronism with the counterpart i222 whereupon the'sprin 566 will slide the counterpart rearwardly for substantial mesh the teeth i253 and iii i i, there- Fishing the higher speed power train in y driving connection between them:-

the propeller. During operation of the s eed power train the clutch actuator will continue to overrun the gear by est-a.

Should-the operator desire to shift downwardi282, enabling these springs and the ciutch counterpart whereby t atter is demeshed from the couuie M iii; i Elli whereupon drive may he resumed througziti the lower speed train hyaceeleratirls the engine for bringing the gear let up to the speed oi the actuator member lit.

i fl'ien the parts of the transmission are at rest the gear III is at rest or is being driven the engine the trait is in he can do so becomes subordinate to the force forwardly together withthe higher speed power train is effective. as a cranking force transmitter from the propeller to the engine, since at this time the clutch teeth I23 and I2 will be in the partially meshed condition illustrated in Fig. 3. Clockwise rotation ofthe propeller, which will usually be manually upon a small craft, will cause clockwise rotation of the driven shaft I02 and of the driven clutch counterpart I22, and since the teeth I24 catch upon the teeth I23 when there is a tendency to rotate the counterpart I22 clockwise relatively to the counterpart I20, the counterpart I20 will likewise be caused to rotate clockwise. Thus the gear H8 is caused to rotate clockwise and the gear Ill and the shafts I04 and IOI rotatively connected therewith are caused to rotate counter-clockwise, which is the direction for cranking the engine assumed to be connected with the transmission.

Cranking force is also transmittable through the higher speed power train from the propeller to the engine should the engine stall while the craft is in flight. If at the time of engine stall the craft should be operated in the higher speed power train, the compression of the engine will quickly decelerate the rotatable parts of the transmission until the gear H8 decelerates to a speed at which the centrifugal weights are forced inwardly by the springs I32 incident to causing adjustment of the clutch I2I to the partial meshed condition. Thereafter by diving the craft suflicient torque can be applied to the propeller by the air stream for rotating it in the clockwise direction that has hereinabove been described for driving the engine through the higher speed power train in the direction for cranking such engine. Forced lubrication is supplied to this form of the transmission from the engine oil pump (not shown) through a channel I50 in the engine block II, a conduit I52 communicating through the rear gear box wall with said channel I50, the hollow central portion of the driven shaft I02 and laterals such as I 53 and I54 which lead radially outwardly of said driven shaft to desired strategic points for the application of the lubriturn of the oil pumped into the gear cant. box to the engine may be by gravity through a back wall opening I55 of said gear box beneath the ball bearing unit I21.

A third form of the invention, shown in Fig. 5. is generally like that shown in Fig. 3..so to expedite this description the parts in Fig. 5 identical with or corresponding to those in Fig. 3 will be designated by the same respective reference numerals with the letter a added, in lieu of a detailed description of such identical or corresponding parts.

No speed responsive control is provided for the clutch counterpart Ia. Instead there is a manually controlled shifter fork 200 having less 20I (of which one is shown in Fig. 5) depending along opposite sides of the clutch I2Ia and fixedupon a cross shaft 202 journalled in the gear box I000. Each of the legs 20I is provided with a shoe member 203 pivotally connected therewith by a pin 20 and which is adapted to press against a circular flange 205 of the counterpart I20a for shifting said counterpart forwardly against the urge of the spring I46a which bears reactively against the web of the gear IIBa. The spring I46a constantly urges the counterpart I20a into mesh with the counterpart I22a, and depending upon the pivotal position of the shifter fork 200, the spring I40 will stop member 208 threaded into an aperture in a boss 209 integral with the gear box mm. A look nut 2I0 is employed for maintaining the adjustment of the stop member 208. When the arm 206 is at position A where it is urged by the spring H611 the counterpart I 20a will be sufficiently far rearward to effect the condition of substantial mesh of the counterparts HM and I22a. However, by rotation of the control lever 206 to the position B the shifter fork 200 will cause its shoes 203 to move the counterpart I20a sufiiciently forwardly to establish the partial meshed condition of th clutch counterparts.

This third form of the transmission is for use primarily with high speed aircraft such as that of the military type pursuit or fighter plane which also generally have propellers of variable pitch. Normally, in the operation of the transmission, since the engine has an abundance of horsepower, take-off will be through the high speed power train which includes the gears Illa, II8a, the clutch I2Ia and the driven shaft H211 to which the propeller is attached.

In order that the propeller of the craft shall operate most efficiently it is necessary that the tips of the propeller blades do not exceed a certain maximum speed. During take-oil, when the craft and hence the propeller has no forward velocity, the propeller can rotate at a higher rate of speed without causing the tips of the blades to exceed said maximum speed than when the craft has a forward velocity that adds a forward component of speed to the circumferential component' due directly to the rotation of the propeller. Moreover, during take-off, it is essential that the variable pitchpropeller be adjusted to a low pitch so it will bite with greater efficiency into the air, and under these conditions the propeller will be rotated at relatively high speed, at which the blade tips have a circumferential speed near said maximum so the craft will be accelerated rapidly. Rotation of the propeller at this high speed, when the pitch is small and the torque relatively low, is more efllciently accomplished by the engine when connected with the propeller through a power train that enables the engine to rotate substantially more slowly than the. propeller. Consequently it is contemplated that the higher speed power train of the embodiment in Fig. 5 will be connected between the engine and the variable pitch propeller during take-off. I

As the craft gains altitude and speed, there is added to the circumferential speed component of the propeller tips a forward component of speed of substantial magnitude which, with said circumferential component, derives a resultant that exceeds said maximum or efllcient tip speed. Therefore, when the forward speed of the craft reaches a speed. at which the propeller loses its efficiency due to said resultant exceeding said maximum, the pilot can increase the propeller pitch, causing it to bite more deeply into the air and thus enabling it to run at a. slower but more as a cranking eflicient speed; 1 Greater torque must be applied tively difierent operating characteristics, said to the propeller under these conditions, however, and so it is at this time that the pilot will shift to the lower speed power train to enable the motor to develop the necessary torque. The lower speed train therefore enables a motor of lower horsepower and weight to drive the propeller at the emcient higher pitch angle and therefore drive the craft at higher speeds. Said shift to the lower speed train is executed at will by simply 1 rotating the control lever 206 to the position B for adjusting the clutch l2la to the partial mesh condition and thus disabling the higher speed power train in its function of transmitting driving force from the engine to the propeller and 1 so the lower speed train comes into use for that purpose.

it will also be noted that when the control lever 2% is moved'to position B so the clutch is in the partial mesh condition, the higher speed train is mobilized ror establishment as a cranking force transmitter between the propeller and engine, as fully explained with respect to the first two embodlments.

While I have herein shown and described but a limited. number. of embodiments of the invention, it will be understood that the invention extends to other embodiments, forms, modifications, structures details falling within the scope spirit ti erect and not sacrificing all oi its material advantages. v

l [in aircraft change-speed transmission corng engine-driven drive shaft, a propellerdriven relatively low and high iving connections individually establishving relation be on said shafts, the connection hung overrunning for peller and operable when set in one of said adjust,- 5 ments to connect its said counterparts for common rotation in both directions to condition said connection for effecting a two-way high speed drive between the engine and propeller, and said clutch being so operable in another of its adjustrun the driven counterpart so that lower speed connection of the transmission may be employed for driving the propeller from the engine, but that the driven counterpart is constrained from tively high speed train is conditioned for the transmission of said cranking force. from the propellerto the engine.

4. In an aircraft change-speed transmission for use between the engine and propeller of such aircraft, a propeller driving connection of relatively low speed, a propeller driving connection of relatively high-speed driving ratio adapting the same for advantageous employment in a vtransmitter between the propeller and engine, said last named connection including a jaw clutch wherein there are drive and driven toothed counterparts respectively rotatable with the en 'gine and propeller and axially meshable to establish said connection in two-wav high speed driving relation between the e the teeth on each counterpai being circumferentially spaced thereabout and having end faces which are generally in opposed relation, axially or the clutch, with said faces on the teeth of the other of said counterparts when the latter are demeshed, the end faces on certain. or" said teeth being bevelled spirally of the clutch. and thus forming pointed edges on said teeth extending generally radially oi the clutch, yielda'ple means having a tendency to maintain a relative axial position of saidcounterparts wherein. their teeth end faces are circumferentially aligned, to cause action is estabhigher speed coh non,

connection for the egm g the said bevelled end faces toratchet over the tooth in gslgonsg end faces opposed thereto during rotation. of the m gri e 511 5:; manipu drive counterpart by the engine at an overspeed m of nov ay relatively to the speed oi the driven counterpart g said higherspeed as during drive or the propeller from the engine m' the drive mission, and to cause said pointed teeth edges to re changuspeed transmission catch. upon the teeth of the counterpart opposed g sngine and i- 1 Such thereto when the driven counterpart tends to g overrun the driveoounterpart and thus condition .7 fgioigeueg' and th s said-relatively high speed connection for tr us a, w g transmitting mittin g said cranking force from the propeller to from propeller to the engine, thaw-angina ingludfli a gm wembje in 5. in a change-speed transmission for use b 1 r t {have haft; tween the engine and the propeller oi g gm an engine-driven drive shaft, propeller tln.

driven shaft, relatively lower and higher 5 transmitting driving connections establishable in driving relation between a shafts, the lower speed connection on. running for adapting it to remain mobilized while the higher speed connection is established and operation, the higher speed connection includ 1g an adjustable clutch wherein there are d ve driven parts respectively rotatable with t e drive and driven shafts, said clutch being normally in one adjustment in which the drive part is free to-overrun thefrlriven part so the driven shaft is drivable from the drive shaft through the lower speed connection without interference by the higher speed connection, but in which adjusthi h pioye employment a between the propeller and en c, said last named connection including clutch means settahle in different adjustments for the same for respec= and propeller,

ments that the drive counterpart is free to overoverrunning the drive counterpart so the rela- 'reversetransmission of power as a cranking iorce ment the driven part is constrained against overrunning the drive part to condition the higher speed connection for transmitting engine-cranking force from the driven shaft to the drive shaft, said clutch being placeable in a second adjustment, upon synchronization of the drive and driven parts, in which said parts are constrained against relative rotation, to establish the higher speed connection in driving relation between said shafts, and means becoming conditioned inresponse to attainment of a'predetermined speed of one of said shafts for placing the clutch in the second adjustment upon the occurrence of said synchronism.

6. In a change-speed transmission for use between the engine and the propeller of an aircraft, an engine-driven drive shaft, a propeller-driving driven shaft, relatively lower and higher speed driving connections individually establishable in driving relation between said shafts, the lower speed connection being over-running for adapting it to remain mobilized while the higher speed connection is established and in operation, the higher speed connection including a clutch wherein there are complemental drive and driven coaxially rotatable counterparts of which the teeth are substantially meshable axially of the clutch to establish said higher speed connection in driving relation between said shafts so the drive shaft can drive the driven shaft therethrough, of which counterpart the teeth are disposable in a partial meshed-relation, and of which counterparts the teeth upon the least one are bevelled spirally of the clutch upon surfaces generally opposed to corresponding surfaces upon the other to facilitate ratcheting of said surfaces during said partial meshed relation while the speed of the drive counterpart exceeds that of the driven counterpart and to facilitate thecatching of the driven counterpart teeth upon those of the drive counterpart when the driven counterpart tends to overrun the drive counterpart and I thus establish the higher speed connection for transmitting an engine cranking force from the dri en shaft to the drive shaft, means for yieldingly urging one of the counterparts to axially approach the other for meshing the teeth, and speed responsive means operable responsively to the speed of one of said shafts in control of said urging means, said speed responsive means being operable at low speeds of said shaft to control said approach of the one counterpart so only said partial meshed relation can exist and operable at higher speeds of said shaft to control said urging means for urging said one counterpart axially farther to establish said substantial meshing of the teeth upon synchronization of the counterparts.

'7. A change-speed transmission comprising drive and driven shafts; a planetary gear unit for drivingly connecting said shafts including a rotatable sun gear, a ring gear connected with the drive shaft for rotation thereby, a planet gear carrier connected with the driven shaft for rotating the same, and planet gears journalled on said carrier and mutually meshed with said sun and ring gears; a one-way holding device operable to prevent backward'rotation of the sun gear while the planet gears react thereon during forward rotation of the drive shaft in the transmission through said unit of forward rotation to the carrier and hence to the driven shaft at reduced speed relatively to the drive shaft; and one-way clutch means having parts respectively connected for rotation with said carrier and one of said gears and relatively rotatable in one direction incurred pursuant to forward rotation of the drive shaft at speeds in excess of that of the driven shaft but non-relatively rotatable in the opposite direction to prevent forward overrun of the drive shaft by the driven shaft, and said one-way clutch means being conditional to prevent relative rotation in either direction between said parts. I

8. A change-speed transmission comprising drive and driven shafts arranged in end-to-end coaxial relation with the driven shaft disposed forwardly of the drive shaft; a planetary gear unit for drivingly interconnecting said shafts including a sun gear rotatable about the driven shaft.

a ring gear concentric with the sun gear and connected with the drive shaft for rotation thereby. a planet carrier drivingly connected with the driven shaft rearwardly of the sun gear, and planet gears join-nailed on said carrier and mutually meshed with said sun and ring gears; a one-way holding device disposed forwardly of the sun gear and operable thereon to prevent backward rotation thereof during forward rotation of the drive shaft in the transmission therefrom-through said unit of forward rotation to the carrier and to the driven shaft connected therewith at reduced speed relatively to the drive shaft: and one-way clutch means disposed rearwardly of said unit, said clutch means including counterparts respectively connected with and for rotation coaxially of and in unison with said carrier and the ring gear, said counterparts being relatively rotatable in one direction incurred pursuantto forward rotation of the drive shaft at speeds in excess of that of the driven shaft but non-relatively rotatable in the opposite direction to prevent forward overrun of the drive shaft by the driven shaft, and said one-way clutch means being conditional to prevent relative rotation in either direction between said counterparts.

9. A change-speed transmission comprising drive and driven shafts arranged in end-to-end coaxial relation with the driven shaft disposed forwardly of the drive shaft; a rearwardly facing driving bell coaxial with the drive shaft and connected for rotation therewith; a planetary gear unit for providing a speed reduction connection between said shafts and including a ring gear on said bell for rotation therewith; a sun gear rotatable about the driven shaft concentrically with the ring gear, a planet gear carrier drivingly connected with the driven shaft rearwardly of the sun gear, and planet gears journalled on said carrier and mutually meshed with the sun and ring gears; a one-way holding device disposed forwardly of the sun gear and operable thereon to prevent backward rotation thereof during forward rotation of the drive shaft, bell and ring gear in the transmission therefrom through said unit of forward rotation to the carr1er and to the driven shaft connected therewith at reduced speed relatively to the drive shaft; an adjustable clutch disposed within said bell and including drive and driven parts respectively rotatable with the drive and driven shafts, said clutch having one adjustment in which the drive part is free to overrun the driven part so the dr ven shaft is drivable at reduced speed from the drive shaft through the planetary gear unit but in which adjustment the driven part is constrained against overrunning the drive part wherefore engine-cranking force is transmittable through said clutch from the driven shaft to the drive shaft, said clutch being placeable in a second adjustment, upon synchronization of the drive and driven parts, in which said parts are constrained against relative rotation in either di rection; and speed responsive means within said bell in control of said clutch and operable upon attainment of a predetermined speed of one of the parts of planetary gear unit and upon the occurrence of said synchronism of said clutch parts to change the clutch from the one adjustment to the second adjustment.

10. In a change-speed transmission for use between the engine and the propeller of an aircraft, an engine-driven drive shaft, a propellerdriving driven shaft, relatively lower and higher speed power transmitting connections individually establishable in driving relation between said shafts, the lower speed connection being overrunning for adapting it to remain mobilized while the higher speed connection is established and in operation, the higher speed connection including an adjustable clutch wherein there are drive and driven parts respectively rotatable with the drive and driven shafts, said clutch having one adjustment in which the drive part is free to overrun the driven part so the driven shaft is drivable from the drive shaft through the lower speed connection without interference by the higher speed connection but in which adjustment the driven part is constrained against overrunning the drive part, said clutch bein placeable in a second adjustment in which the parts are constrained against relative rotation in both directions to establish the higher speed connection in driving relation between said shafts, yieldable means normally maintaining said second adjustment, and means manipulatable during operation of the higher speed connection for effecting the second adjustment and thus demobilizing such higher speed connection.

OSCAR. H. BANKER. 

